Solar Thermal Power System for Oxygen Production from Lunar Regolith

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The Optical Waveguide Solar Energy System Used for. Hydrogen Reduction of JSC-1 and Ilmenite (1996). SBIR Phases I and II supported by NASA/JSC:.
Physical Sciences Inc.

VG09-193

Solar Thermal Power System for Oxygen Production from Lunar Regolith Takashi Nakamura and Benjamin K. Smith Physical Sciences Inc. Pleasanton, CA AIAA Space 2009 Conference and Exposition 14-17 September 2009 Pasadena, CA

Physical Sciences Inc.

20 New England Business Center

Andover, MA 01810

Solar Thermal System for Oxygen Production from Lunar Regolith

Physical Sciences Inc.

Concentrator Array

Optical Waveguide Cable

VG09-193-1

High Intensity Solar Thermal Power

Lunar Regolith

Oxygen Thermochemical Processing H-3796a

• • • •

Transmission of high solar flux via flexible optical waveguide Scale up by incremental increase of concentrator units Transportable and deployable on the lunar surface Multi-use for a variety of oxygen production processes

The Optical Waveguide Solar Energy System Used for Hydrogen Reduction of JSC-1 and Ilmenite (1996) Physical Sciences Inc. VG09-193-2

SBIR Phases I and II supported by NASA/JSC: Dr. Carlton Allen; Dr. David McKay; Dr. Wendell Mendell (COTR)

Thermal Reactor with Optical Fiber Cables Physical Sciences Inc. VG09-193-3

Material Processing Container Physical Sciences Inc. VG09-193-4

Material Processing Experiment Physical Sciences Inc. VG09-193-5

Hydrogen reduction of iluminite: FeTiO3 + H2 → Fe + TiO2 + H2O @ 800 C ~ 1100 C

Material sample: Lunar soil simulant (JSC-1) containing 3 wt% of iluminite

Reaction detection: Absorption of a water line at 1.36 µm

Thermal Reactor Temperature versus Solar Power Physical Sciences Inc. VG09-193-6

1000

Temperature (ºC)

800 3/18/96

600

3/19/96 3/23/96, moly rad shields added 3/26/96 4/13/96, moly sleeve insert added

400

4/27/96

200

4/29/96 5/9/96 least square fit

0

0

40

80 120 160 Power Input (W)

200 D-3092

Cable Inlet Optics (Previous Technology) Physical Sciences Inc. VG09-193-7

Quartz Secondary Concentrator Total Internal Reflection

Solar Ray from Primary Concentrator

Optical Fiber Cable

D-3083a

Optical Fiber Cross Section C-9711

Fill factor = 0.73 ~ 0.82

Cable Inlet Optics (New Technology) Physical Sciences Inc. VG09-193-8

Reflective Matrix Secondary Concentrator

Testing of Cable with New Inlet Optics (5/7/07) Physical Sciences Inc. VG09-193-9

7-Fiber Cable (1.2 mmφ; 3.14 m) Focus Point Power Measurement

S.C.

Power Output Measurement J-3746

• • • •

Focus Flux Intensity: Power Input to S.C.: Power Output: Transmission Efficiency:

167 ~182 W/cm2 31.40 W 21.70 W 69.10% including Fresnel Loss (previous 52 ~ 55%)

Solar Test of Cable with New Inlet Optics Physical Sciences Inc. VG09-193-10

Cable Test with PSI Concentrate Cable Transmission (3.14 m): 69%

Pathway for Component Efficiency Improvement Physical Sciences Inc. VG09-193-11

Component

1996-2005

May 2007

Space-Based Operational System

Improvement Measures

Concentrator

0.722

0.722

0.912

Reflectivity

0.82

0.82

0.950*

• Protected silver coating

Intercept factor

0.88

0.88

0.96

• High slope accuracy and in the absence of atmospheric scattering

0.526

0.691

0.812

0.965 0.734 0.77

0.965 1.0 0.74

0.983 1.0 0.84

Back Fresnel ref

0.965

0.965

0.983

System Efficiency

0.38

0.499

0.740

Optical Fiber Cable Front Fresnel ref Fiber fill factor Integral fiber transmission

• AR coating (650~1100 m) • Already accomplished • Improved inlet optics and high purity fiber • AR Coating (650~1100 m)

* Reflectivity of protected silver: 0.975. Reflected Cassegrain concentrator: 0.975 x 0.975 = 0.950.

Receiver Interface with Oxygen Production Process Physical Sciences Inc. VG09-193-12

• Hydrogen reduction of lunar regolith (850-1000C) – Temperature easily attained – Thermochemical process demonstrated

• Carbothermal lunar regolith processing (CLRP; 1600-1800C) – High temperature requirement – Main focus of Phase I work Optical Fiber Cable

Quartz Rod

Focusing Optics

Regolith Melt

Regolith Bed

Radiation Flux

Reactant Gas

Temperature

∆T = Γ ∼ ∼ 300 K/mm κ ∆X

Melt Screen

Liquid Melt Zone Surface Regolith

Reacted

Imaging Optics

H-5389

Non-imaging Optics

Regolith

J-2362

Melting JSC-1 with Xe-Arc Light Source Physical Sciences Inc. VG09-193-13

Imaging Optics

Non-imaging Optics

Melting JSC-1 with Solar Heat: I Physical Sciences Inc. VG09-193-14

Two Cables Focused on a Single Point

Power: 104 W Peak Flux: 84.4 W/cm2 Temperature: 1556 C

Melting JSC-1 with Solar Heat: II Physical Sciences Inc. VG09-193-15

Three Cables Focused on a Single Point Power = 145 W Peak Flux = 117.4 W/cm2 Temperature = 1728~1800 C

Vitrified JSC-1 Melt: 14 mm dia

Surface Temperature of JSC-1 Melt Physical Sciences Inc. VG09-193-16

2500

Temperature (C)

2000

1500

1000 Orbitec CO2 Laser PSI Solar

500

PSI Solar (unsteady) PSI Xe Arc

0 0

50

100 150 Flux (W/cm2)

200

250 J-3836

Temperature measured by Type C (W 5% Re - W 26% Re) thermocouples

Physical Sciences Inc.

Solar Thermal System: Ground-based Engineering Model VG09-193-17

• Developed and undergoing test in 2009

Solar Concentrator Array Physical Sciences Inc. VG09-193-18

Solar Tracking Accuracy: 0.04 degree

Physical Sciences Inc.

Solar Thermal System: Ground-based Engineering Model VG09-193-19

• 7-Optical Fiber cables connected to a single quartz rod

Carbothermal Reactor Interface Optics Physical Sciences Inc. VG09-193-20

Single Quartz Rod Emitting solar Power (~ 750W)

Solar Power Output from the Quartz Rod as Projected on the Metal Screen

Physical Sciences Inc.

VG09-193-21

Power Output Intensity: 137 W/cm2 measured at solar flux of 800 W/m2

Solar Power Output from the Quartz Rod Physical Sciences Inc. VG09-193-22

900 800 700 600 500 400 300 200

Measured Power at 800 W/sqm (3/23/09) Adjusted Power for 880 W/sqm

100 0 0

1

2

3

4

# of Mirror/Cable

5

6

7

8 K-1275

Performance Characteristics Summary Physical Sciences Inc. VG09-193-23

System/Component Solar Flux at Test Site (San Ramon, CA) Concentrator Area (Effective): note (i)

Values 880 W/m2 0.341 × 7 = 2.387 m2

Concentrator (Cassegrain configuration) Primary Mirror Reflectivity (measured): note (ii)

0.91

Secondary Mirror Reflectivity (manufacturer data): note (iii)

0.95

Intercept Factor (measurement data): note (iv)

0.72

Concentrator Efficiency

0.91 × 0.95 × 0.72 = 0.6224

Optical Fiber Cable (Inlet Optics and Optical Fiber) Cable Transmission (based on measurement data)

0.70

Solar Power System (Concentrator and Cable) Solar Power System Efficiency

0.6224 × 0.70 = 0.4357

Reactor Interface Optics Transmission of Interface Layer (calculated): note (v)

0.875

Solar Power System for Carbothermal Reactor Overall System Efficiency

(i) (ii) (iii) (iv) (v)

0.4357 × 0.875 = 0.3812

Solar Power Delivery to Reactor (calculated)

880 × 2.387 × 0.3812 = 801 W

Solar Power Delivery to Reactor (measured)

795 W

excluding shadowed area Aluminum mirror protected Silver mirror a measure of focusing capability cooling water film between the fiber outlet and the quartz window/rod

Improvement Options Physical Sciences Inc. VG09-193-24

Current Ground-based Engineering System

Improvement for Ground-based Engineering System

Primary Mirror Reflectivity

0.91

0.95

Secondary Mirror Reflectivity

0.95

0.95

Intercept Factor

0.72

0.88

0.91 × 0.95 × 0.72 = 0.6224

0.95 × 0.95 × 0.88 = 0.7942

0.70

0.8

0.6224 × 0.70 = 0.4357

0.7942 × 0.8 = 0.6354

0.875

0.938

0.4357 × 0.875 = 0.3812

0.6354 × 0.938 = 0.596

Concentrator (Cassegrain Configuration)

Concentrator Efficiency Optical Fiber Cable (Inlet Optics and Optical Fiber) Cable Transmission Solar Power System (Concentrator and Cable) Solar Power System Efficiency Reactor Interface Optics Transmission of Interface Layer Solar Power System for Carbothermal Reactor Overall System Efficiency

Solar Thermal System for Oxygen Production: Summary Results and Current Status

Physical Sciences Inc.

VG09-193-25

• Solar thermal system based on the optical waveguide (OW) technology is viable and effective for oxygen production from lunar regolith • Solar thermal power is capable of heating the lunar regolith to the temperatures necessary for oxygen production • The ground based engineering system was built and is being tested with the carbothermal oxygen production reactor • Performance enhancement will be achieved by incremental improvement of system components

Acknowledgements Physical Sciences Inc. VG09-193-26

The programs reviewed in this paper were supported by: • •

NASA/JSC through SBIR Phase I and II (NNJ07JB26C and NNJ08JD44C, COTR: Mr. A. Paz); and NASA/GRC through SBIR Phase III (NNC08CA59C, COTR: Dr. A. Hepp).

The Phase I and II programs were conducted in collaboration with Lockheed Martin Space Systems Company (LMCO, Mr. L. Clark) and Orbital Technologies Corporation (ORBITEC, Mr. R. Gustafson).